The following information is provided to assist the reader in understanding the devices, systems and/or methods disclosed below and the environment in which such devices, systems and/or methods will typically be used. The terms used herein are not intended to be limited to any particular narrow interpretation unless clearly stated otherwise in this document. References set forth herein may facilitate understanding of the devices, systems and/or methods or the background. The disclosure of all references cited herein are incorporated by reference.
A supplied-air respirator such as self-contained breathing apparatus (SCBA) permits a person to breath in hazardous environments such as fires and confined spaces where breathing would be difficult or impossible without mechanical aid. A supplied-air respirator may, for example, include a full facepiece, a harness and carrier assembly, a gas cylinder containing high pressure compressed air (or other oxygen containing gas) for breathing and at least one, and more typically two, pressure regulators. The first or first-stage regulator is typically mounted near the air cylinder and functions to reduce the relatively high pressure of the compressed air from the air cylinder to above atmospheric pressure. The air cylinder typically contains air (or other breathable gas) under a relatively high pressure of, for example, 2200 psi to 4500 psi. The first stage regulator may, for example, reduce the pressure to about 80-100 psi. The second or second-stage regulator is typically mounted on the facepiece and functions to adjust the flow of air to meet the respiratory needs of the user. Respiration-controlled regulator assemblies are disclosed, for example, in U.S. Pat. Nos. 4,821,767 and 5,016,627.
The facepiece or face mask, which is sealed to the face of the user, typically includes a lens through which the user can view the surrounding environment. The facepiece also includes an interface or mount for fluid connection with the second-stage regulator through which inspired air passes into the face mask and an exhalation port through with expired air passes out of the mask. In some facepieces, a single port is used for both inspired and expired air. In other facepieces, separate ports are used. The user's respiration controls a valve system (for example, including an inhalation valve and an exhalation valve) to control delivery of pressurized air via the second-stage regulator. Often, it is desirable to maintain a slight positive pressure within the facepiece relative to ambient pressure. Facepieces for supplied-air respirators in which a positive pressure is maintained within the facepiece are often referred to as pressure demand facepieces, while other facepieces for supplied-air respirators are often referred to as demand facepieces.
It is often desirable to provide information to the user of a breathing apparatus, including, for example, data on the status of the air supply, power supply and/or other systems of the breathing apparatus, information on other users in the vicinity of the user, evacuation alerts and/or other information. Informational displays have been provided to users of a breathing apparatus in a number of manners. For example, a display may be provided in the vicinity of the second stage regulator. A display may alternatively be provided on an outer portion of the lens. In the case of displays exterior to a facepiece of a breathing apparatus, smoke or other environmental conditions could obscure the user's vision of the display unless it is located very close to the lens of the facepiece. Moreover, harsh environmental conditions can adversely affect the operation the display. Also, care must be taken in the case of positioning a display in the vicinity of the facepiece lens not to overly obstruct the field of view of the user.
Providing a display within the interior of the facepiece can eliminate one or more of the adverse effects of the surrounding environment on the display, but can present other problems with, for example, adequately sealing the passage of electronics through the facepiece to communicate with the display. Although use of a powered display within the facepiece that communicates wirelessly with electronics external to the facepiece can eliminate the problems associated with passing electric wires and/or electronics through the facepiece, a dedicated power supply within the facepiece is still required to power the display. Moreover, the display and associated electronics within the facepiece can increase manufacturing costs as well as maintenance time and costs.
Whether a display is provided internal to the facepiece or attached externally thereto, currently available displays can negatively impact the weight of the facepiece, the center of gravity of the facepiece, the field of view of the user, the cost of the facepiece and/or other aspects of the facepiece.